Introduction  to  the  HYSPLIT  Trajectory  Model

WMO  GURME  Regional  Training  Workshop  on  urban  air  quality  modelling  for  ASEAN  Countries  

Malaysian  Meteorological  DepartmentPetaling Jaya,  7  -­‐ 10  April  2015

Slides  from  ARL  tutorials  and  presentations  

Introduction

http://www.ready.noaa.gov/ready/open/hysplit4.html

HYSPLIT  can  be  run  directly  via  the  internet

They have only translated a few things for now, but are working to make the site fully translated into Spanish

http://www.ciecem.uhu.es/hysplitweb08/HYSPLIT.php

Spanish  Version  HYSPLIT  Web  Site  being  developed  in  Spain:

Meteorological  Data

HYSPLIT  requires  at  a  minimum,  u,v,w,T,  Psfc (RH  or  Q  optional)  in  3  dimensions

Meteorological  data  are  specially  formatted  to  minimize  execution  time

Compressed  binaryFields  are  written  at  each  level  for  one  time  period,  then  repeated  as  needed  in  time

All  forecast  data  currently  available  in  HYSPLIT  menus  originates  from  NOAA’s  National  Centers  for  Environmental  Prediction  (NCEP)

Forecast  or  AnalysisRegistration  is  required  to  run  HYSPLIT  dispersion  with  forecast  dataData  is  available  globally  and  regionally  over  North  America

PC  HYSPLIT  downloads  data  directly  from  NOAA  ARL  servers;  options  are  available  to  switch  to  other  FTP  servers

Introduction

Meteorological  Data

ForecastMeteorological  Data:North  American  Meso  (NAM)Rapid  Update  Cycle  (RUC)Global  Forecast  System  (GFS)

For  more  information,  see  the  following  websites:

http://www.arl.noaa.gov/READYmetdata.php

http://www.arl.noaa.gov/archives.php

http://www.nco.ncep.noaa.gov/pmb/products/

Analysis Meteorological  Data:North  American  Meso  (NAM)NAM  Data  Assimilation  System  (NDAS,  formerly  EDAS)Global  Data  Assimilation  System  (GDAS,  formerly  FNL)Global  Reanalysis

Supplement

Measurement  of  ambient   air  

concentrations

Height  of  Planetary  Boundary  Layer  (PBL)  During  the  Day

Greater  than  ~20km  from  the  source,  if  the  forward  trajectory  from  the  source  is  within  the  PBL,  then  the  source  can  impact  the  measurement  site,  even  if  the  trajectory  endpoint   near  the  site  is  not  at  the  height  of  the  sampler…  This  is  because  the  PBL  is  relatively  well-­‐mixed  during   the  day.

Measurement  of  ambient   air  

concentrations

q a  forward  trajectory  is  the  “center  line”  of  a  plume  

q horizontal  &  vertical  dispersion  around  this  center  line

Height  of  Planetary  Boundary  Layer  (PBL)  At  Night

q At  night,  the  Planetary  Boundary  Layer  (PBL)  is  generally  much  shallower

q Emissions  from  an  elevated  stack  may  be  emitted  above  the  PBL  

q In  this  case,  little  or  no  impact  on  a  ground-­‐based  measurement  site  until  the  next  daytime  period,  when  the  boundary  layer  grows.

Measurement  of  ambient   air  

concentrations

Height  of  Planetary  Boundary  Layer  (PBL)  At  Night

q At  night,  the  Planetary  Boundary  Layer  (PBL)  is  generally  much  shallower

q Emissions  from  an  relatively  low  stack  may  be  emitted  within  the  PBL  

q But,  if  the  pollutant  dry  deposits  relatively  rapidly  (e.g.,  reactive  gaseous  mercury  (“RGM”),  by  the  time  the  plume  reaches  the  receptor,  there  may  be  little  pollutant  left…  

Measurement  of  ambient   air  

concentrations

dry  deposition  can  deplete  near-­‐ground  plume

PBL  Height

q What  are  the  implications  of  these  ideas  for  back-­‐trajectories?

q What  HEIGHT  should  one  start  a  back-­‐trajectory?

q If  you  start  very  low  to  the  ground,  at  the  sampler  height,  the  trajectory  program  does  not  work  well…  the  trajectories  hit  the  ground  and  stop

q “best”  starting  height  for  back-­‐trajectories  may  be  from  the  middle  of  the  Planetary  Boundary  Layer    

Measurement  of  ambient   air  

concentrations

H  =  0.5  *  PBL  

Applications:  Air  masses  origin

Allen  et  al.,  2011

Dry  and  wet  deposition  of  the  pollutants  in  the  puff  are  estimated  at  each  time  step.

The  puff ’s  mass,  size,  and  location  are  continuously  tracked…

Phase  partitioning  and  chemical  transformations  of  pollutants  within  the  puff  are  estimated  at  each  time  step

=  mass  of  pollutant(changes  due  to  chemical  transformations  and  deposition   that  occur  at  each  time  step)

Centerline  of  puff  motion  determined  by  wind  direction  and  velocity

Initial  puff  location  is  at  source,  with  mass  depending  on  emissions  rate

TIME  (hours)0 1 2

deposition  1 deposition  2 deposition   to  receptor

lake

Lagrangian  Puff  Atmospheric  Fate  and  Transport  ModelNOAA  HYSPLITMODEL

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